Isolation of a novel glycyrrhizin metabolite as a causal candidate compound for pseudoaldosteronism

Osamu Morinaga,Yasuhito Maki,Toshiaki Makino,Kan’Ichiro Ishiuchi,Tomoya Yasujima,Takeshi Ohkita,Hiroaki Yuasa,Miaki Mitamura,Asuka Hirasawa,Chuanting Tian

doi:10.1038/s41598-018-33834-9

Osamu Morinaga, Yasuhito Maki + Show 8 more

Open Access

https://doi.org/10.1038/s41598-018-33834-9

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Abstract

Pseudoaldosteronism is a common adverse effect associated with traditional Japanese Kampo medicines. The pathogenesis is mainly caused by 3-monoglucuronyl glycyrrhetinic acid (3MGA), one of the metabolites of glycyrrhizin (GL) contained in licorice. We developed an anti-3MGA monoclonal antibody (MAb) and an ELISA system to easily detect 3MGA in the plasma and urine of the patients. However, we found that some metabolites of GL cross-reacted with this MAb. Mrp2-deficient Eisai Hyperbilirubinemia rats (EHBRs) were administered glycyrrhetinic acid (GA), and we isolated 22α-hydroxy-18β-glycyrrhetyl-3-O-sulfate-30-glucuronide (1) from the pooled urine with the guidance of positive immunostaining of eastern blot as the new metabolite of GL. The IC50 of 1 for type 2 11β-hydroxysteroid dehydrogenase (11β-HSD2) was 2.0 µM. Similar plasma concentrations of 1 and GA were observed 12 h after oral administration of GA to EHBR. Compound 1 was eliminated via urine, whereas GA was not. In Sprague–Dawley (SD) rats orally treated with GA, compound 1 was absent from both the plasma and the urine. Compound 1 was actively transported into cells via OAT1 and OAT3, whereas GA was not. Compound 1, when produced in Mrp2-deficiency, represents a potential causative agent of pseudoaldosteronism, and might be used as a biomarker to prevent the adverse effect.

Highlights

Pseudoaldosteronism is a common adverse effect of traditional Japanese Kampo medicine
A clinical study reported that the plasma concentrations of 3-monoglucuronyl-glycyrrhetinic acid (3MGA), another metabolite of GL (Fig. 1), was significantly higher in a patient group treated with GL with hypokalemia than in a group with normal potassium levels
We showed that 3MGA was present in plasma and urine when multidrug resistant-association protein (Mrp) 2, a transporter involved in bile excretion, was impaired7. 3MGA is a substrate of the organic anion transporters (OATs) 1 and OAT3, and is actively transported from the plasma into tubular epithelial cells where it inhibits 11β-HSD2, GA is not a substrate of these transporters[8]

Summary

Introduction

Pseudoaldosteronism is a common adverse effect of traditional Japanese Kampo medicine. Detection of pseudoaldosteronism is critical to prevent disease aggravation caused by Kampo medication. Licorice is prescribed frequently in Kampo medicine to treat a variety of diseases. GA, a major metabolite of GL, inhibits type 2 11β-hydroxysteroid dehydrogenase (11β-HSD2) in renal tubular epithelial cells, resulting in an elevation in cortisol levels, a potent agonist of mineralocorticoid receptors, leading to increased sodium retention and potassium excretion[5]. A clinical study reported that the plasma concentrations of 3-monoglucuronyl-glycyrrhetinic acid (3MGA), another metabolite of GL (Fig. 1), was significantly higher in a patient group treated with GL with hypokalemia than in a group with normal potassium levels. Plasma and urine 3MGA may be used as a biomarker to find early onset of pseudoaldosteronism

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